Self-checkout terminals at grocery stores and other retail stores are well known. The terminals permit a consumer to present items for purchase to sensors at the terminal so the terminal can identify the items and a corresponding price. When the consumer indicates all items for purchase have been presented to the terminal, a sub-total is accumulated, any taxes and discounts are computed, and a total amount due is displayed for the consumer. The terminal then allows the consumer to select a payment method. The terminal presents menu selections to the consumer so funds are transferred to the retailer's account. Upon confirmation of payment, the items are released to the consumer.
A self-checkout terminal typically includes a display, a scanner for reading unit price codes (UPC), and a checkout area for holding items once they have been scanned. The terminal also includes a processor, memory, programmed instructions, and data peripherals to control the operations of the terminal. The programmed instructions may contain modules for querying for item prices, computing totals and performing other functions related to the purchase of items through a self-checkout terminal. Some checkout terminals may also include a security application program that operates to reduce the likelihood that the consumer leaves without scanning all of the items or exchanges scanned items with more expensive items that have not been scanned. In many self-checkout terminals, the surface area of the checkout area has a scale underneath it to help track items during checkout. By monitoring the weight of items placed on the checkout area, the security application is able to determine some actions of the consumer for purposes of detecting fraud or operator error by a consumer. For example, the change in weight detected by the scales of the checkout area may be used to determine the weight of an item just placed on the checkout area. This item weight may then be compared to the weight of the item last scanned that is stored in a database or other memory. If the weights are different, the security application program notifies the consumer and prompts the consumer to remove the item and scan the item again to rectify the discrepancy. Thus, the application program is capable of tracking the scanning of items and their placement on the checkout area through its monitoring of the scales associated with the checkout area.
While this type of item monitoring is useful for security tracking purposes it does have some drawbacks. For one, items having the same weight as one or more items placed on the checkout area may be exchanged without detection by a security application that only monitors total weight at the checkout area. For example, one liter bottles of a beverage may be exchanged without detection because the security application would detect the removal of an item weighing the equivalent of a one liter bottle from the scale and the return of an item having the same weight. However, if the item returned to the scale was not a one liter bottle but one or more items having the same weight as the one liter bottle, the security program would not likely detect the exchange because the total weight before and after the exchange is the same.
In order to track the items in the checkout area in a more effective manner, the security program needs more data regarding the items for detection of exchanges.
What is needed is a method of tracking individual item characteristics in the checkout area rather than relying upon a single characteristic to which all of the items contribute.